Small, hand held tubing cutters have been in wide use for many years for severing certain pipes as well as metal, plastic and glass tubing, in each instance to a specific length. One early patent was that of Gallagher and Grimes, U.S. Pat. No. 1,107,511 and entitled "Pipe Cutting Appliance," which issued Aug. 18, 1914. This device was particularly designed for severing vertically disposed pipes located somewhat below ground level. Accordingly, this device utilized a pair of rotary cutters disposed at the lower ends of a pair of pivotally mounted legs, with these legs being of elongate configuration so as to extend down into a hole in the ground in which the pipe to be cut was located.
By forcing the pair of legs together, the rotary cutters could be brought into firm contact with the pipe to be cut. Although the Gallagher and Grimes patent was apparently satisfactory for the intended purpose, it was limited in its use in that it could only be attached to an open ended pipe or tubing. Also, it was not well suited for severing tubing of comparatively small diameter, particularly if the tubing was being held in the hand.
A device much more appropriate for cutting small tubing to a precise length was taught in the Myers U.S. Pat. No. 1,945,949 entitled "Tube Cutter." This device was constructed to utilize a closely spaced pair of rollers disposed in a generally opposed relationship to a cutting wheel, with the tubing to be cut placed therebetween. A spring biased threaded screw arrangement provided with a knurled tightening knob made it possible for a user to cause the cutting wheel to make successively deeper circumferential cuts until the tubing is finally severed. Devices of this type were usable in a highly advantageous manner in the field, because they were of such small size that they could be carried in the craftsman's pocket.
Importantly, Myers utilizes a single threaded shaft, which does not manipulate the components as rapidly as does a dual threaded shaft, and in addition, Myers introduces a clutch mechanism to his tubing cutter. As is obvious, the addition of the clutch members significantly increases the cost of manufacture of the Myers device.
Another device of the prior art was the Pierson U.S. Pat. No. 2,631,411, which was specifically designed for cutting glass tubing, with the Pierson device utilizing a pair of levers of similar length, which are pivotally secured together at one end. A rotary cutting wheel was disposed at the opposite end of the Pierson device, with a finger operated tightening knob operatively disposed on a single threaded rod being utilized at an intermediate location for bringing the two levers tightly together at the time the user wished to sever glass tubing. However, the Pierson patent utilized a spring means tending to bias the levers apart, which meant that the spring means was in a sense at cross purposes with the tightening means. In addition, the single threaded shaft 23 of Pierson often extended for a significant distance beyond all other components of the device, thus inviting possible damage as well as requiring additional storage space.
Still another pertinent device of the prior art was the Hofmaster U.S. Pat. No. 2,743,520, which device was described by the patentee as being of "plier-like configuration." The Hofmaster patent utilizes a tightening means located between the pivot point and the location where his cutting wheel is operatively disposed in conjunction with a roller means. As a consequence of this arrangement, the user needed to continue to apply a tightening effort to the tightening means, to cause the cutting wheel to eventually sever the tubing at the selected location.
When the user desired to utilize the Hofmaster device in cutting a rod or the like, the jaws 15 and 24 are spread apart by appropriate movement of bolt 33, to permit an insertion of the rod 14 between the cutting roller 20 and the pressure rollers 30. As illustrated in FIG. 1 of Hofmaster, the rollers are axially parallel with the axis of the rod 14, so the full length of the pressure rollers 30 are in contact with the rod. However, it is important to note that the radial arc generated by jaw 24 when adjusting this cutting device to rods of other diameters will cause the rollers 30 to no longer be axially parallel with the rod 14, and as a consequence, only the outer edges of the rollers 30 will be in contact with the rod. Also, the full length of this cutting device must lie parallel to a pipe during the cutting procedure or else it may be impossible to deal with obstructions such as bends in the pipe or couplings in the pipe that are in a close relationship to the location where the severing is to take place.
It was in an effort to overcome the disadvantages of these and other such patents that the present invention was evolved.